Molecular dynamics description of grafted monolayers: effect of the surface coverage.
Molecular dynamics simulations of monolayers of metal-chelating ligands grafted onto a graphite surface in water are carried out to calculate structural (density profiles, radius of gyration, and asphericity coefficients), dynamical (diffusion coefficients), and energetical properties as a function of the surface coverage. The purpose is to provide a better understanding of the dependence of various properties of these monolayers on the surface coverage. A critical value of the surface coverage from which all structural properties derive a limiting value has been established. It also appears that the chains rather adopt an elongated conformation along the direction normal to the surface from this critical surface coverage. The hydrogen-bonding structure and dynamics of water molecules are reported. An ordered structure of water in the region close to the terminal groups of the grafted molecules is shown at a relatively high surface coverage. This ordering is similar to that observed in the case of water in interaction with a solid surface.
Goujon
F
F
Laboratoire de Thermodynamique et Interactions Moleculaires de l'Universite Blaise Pascal (Clermont-Ferrand II), FRE 3099, 24 Avenue des Landais, 63177 Aubiere Cedex, Paris Cedex 05, France.
Bonal
C
C
Limoges
B
B
Malfreyt
P
P
D002614:Chelating Agents / Q000737:chemistry; D004058:Diffusion; D006108:Graphite / Q000737:chemistry; D006860:Hydrogen Bonding; D008670:Metals / Q000737:chemistry; D008958:Models, Molecular; D055672:Static Electricity; D013499:Surface Properties; D014867:Water / Q000737:chemistry
D002614:Chelating Agents; D008670:Metals; D014867:Water; D006108:Graphite